It is known from EP 1671901 that there exists a circuit for the supply of power and for controlling of a conveyor roller, driven by an electric motor, which circuit includes a hollow body, in which an electric motor is located, and where the hollow body rotates on an axis. The electric motor is coupled to the roller body by components used to drive the said roller body and to transfer torque, and by a power supply cable supplying power to the electric motor, and by at least two, and preferably three position sensors. An electronic commutation device is also provided, which electronic device may be incorporated in the roller or in the electric motor, or may be an external device. The position sensors are designed to generate signals related to the position of the stator in relation to the position of the rotor of the electric motor. The used electric motor is of the brushless three-phase type with an internal rotor. The bearing element of the electric motor, which represents a hollow shaft component, usually is integrated with a cable and a connector. The connector is designed to connect the electric motor to the control device. The connector incorporates three connecting terminals to the coils, two terminals for supplying power to the position sensors, as well as one output signal terminal for each position sensor. Thus, the number of terminals used in the connector amounts to eight, which is exceptionally impractical and results in a number of deficiencies of the known conveying roller driven by an electric motor; these deficiencies are related to difficult assembly and a lack of assembly space. Thus, in a version using an external commutation device, the main deficiency is related to limitations on the selection of the power output of the electric motor depending on the thickness of the power supply wires and the large number of terminals, as described above and to the maximum admissible assembly orifice for the assembly of the hollow shaft component of the bearing element of the electric motor to the supporting element of the conveyor. With the option with an internal commutation device, higher operational loads result in the transfer of a substantial quantity of heat into the roller body from the electric motor located therein, which heat cannot be discharged to a sufficient degree because of the encapsulation of the roller. This substantially limits the admissible operational loads.
It is known from U.S. Pat. No. 6,710,505 B1 a power supply and control circuit for a motor-driven conveying roller, where the conveying roller incorporates a hollow body of the roller rotating on an axis, in which hollow body an electric motor is incorporated and coupled to the hollow body of the roller by elements for driving the roller body and for the transfer of torque. In this body a cable is also incorporated with respective terminals, connected to a connector, from the coils of the electric motor. There is one first potential terminal for supplying power to the included position sensors with signal outputs and the number of position sensors with signal outputs may be at least one, which position sensors are supplied with power from the first potential terminal, There is one more signal output—to provide a signal to the controller when a roller is stuck. So, the number of terminals used in the connector amounts to minimum five, but they are usually seven, which is impractical and results in deficiencies are related to difficult assembly and a lack of assembly space. The deficiencies highlighted above apply also to this known solution, which deficiencies are related to limitations on the selection of the power output of the electric motor and to the maximum admissible assembly orifice for the assembly of the hollow shaft component of the bearing element of the electric motor to the supporting element of the conveyor,
It is known from the DE 10 2008 047 494 a power supply and control circuit for DC motor in particular for an electronically controlled brake system. It includes the phase windings electrically powered via a inverter circuit, In order to match vote rotation and speed between the rotor and spin boxes in the phase windings and for a secured start-up under load, the stator incorporates three rotation sensors, which scan the rotor. These sensors outputs are connected via a common line to a downstream common control, and thus phase-shifted output signals for further processing in a downstream common control is emitted. The output signals of the rotation sensors commute according to the rotor behaviour periodically between a high level and a low level. The outputs of rotation sensors are connected to a known electrical resistance. All rotation sensors are connected parallel to each other and, as group, are connected to a star point S of the phase windings to provide electric power of the rotation sensors. In order to stabilize the supply of the rotation sensors, they are connected upstream of at least one R/C element within the formed supply circuit, and the additional electrical resistance generates a voltage drop in order to adapt each phase voltage to the required supply voltage of about 5V. Furthermore, a Zener diode, connected to ground and correspondingly is included after the electrical resistance connected to the rotation sensors.
This known solution has a very specific application and may not be, used for power supply and control circuit for a motor-driven conveying roller, as it includes a substantial number of components used for specific purposes outside the sphere of application in conveyors, and moreover the electric circuits to and from the sensors may not be directly applied to the power supply circuit of the roller as they make the problem with the limited assembly space even more complex. In addition, the status of the rotation sensors is encoded as electrical resistance (analog coding) and requires additional space.